Some Effects of General Yellow Rust (Puccinia striiformis) Infection on14Carbon Assimilation, Translocation and Growth in a Spring Wheat

Abstract

A general, heavy infection of Yellow Rust(Puccinia Striiformis Westend.) on the leaf laminas of the spring wheat (Triticum vulgare Host) Jufy I, unlike an infection on one leaf only, modified the distribution pattern of ¹⁴C-labelled assimilate translocated from the second leaf: the proportion moving to the roots (in older plants also to the tillers) was decreased, and that moving to the leaves was increased. The proportion of the assimilate translocated out of an infected leaf of a such plant was, however more than that observed when that leaf was the only one infected, though still less than that from a corresponding leaf in a healthy plant. Age of leaf did not greatly affect the distribution pattern. The effect of infection on the distribution pattern of assimilate from other leaves 15 days after inoculation was comparable to the effect on that from the second leaf at the same interval after inoculation. In the case of the upper leaves the proportion moving to the tillers was appreciably reduced by infection. These results are considered in relation to data obtained from a parellel growth analysis experiment, with which they are in good agreement.